Pressure-atomizing type oil burner having a high-frequency vibratory-piston oil-supply pump



PRESSURE-ATOMIZfNG TYPE OIL BURNER HAVING A HIGH-FREQUENCYVIBRATORY-PISTON OIL-SUPPLY PUMP Filed Jan. 30, 1952 5 Sheets-Sheet l z;70/445? ll i 5 69% w? Q; 144 8 64 14 35/ INVENTORS June 22, 1954 P. H.BILLS ETAL 2,681,695

PRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCYVIBRATORY-PISTON OIL-SUPPLY PUMP 5 Sheets-Sheet 3 Filed Jan. 30, 1952 NH a ml 1 7 M 6 6 9 Mm m n y M w A 0 .J i 6AM a a m u a m w m M m g m1 Wm vv l ii liarg ficiw June 22, 1954 Filed Jan. 30, 1952 P. H. BILLS ETAL 2,681,695 PRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCYVIBRATORY-PISTON OIL-SUPPLY PUMP 5 Sheets-Sheet 4 INVENTOFZS FH l LIP H.B ll l S JOSEPH A. LOGAN THEODORE J. MESH ATTORNEYS June 22, 1954 P. H.BILLS ETAL PRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCYVIBRATORY-PISTON OIL-SUPPLY PUMP Filed Jan. 30, 1952 5 Sheefcs-Sheet 5FIG-J12 FIG.II

TIME IN SIYTIETH OF SECONDS TIME IN SIXTIETHS OF SECONDS TIME INSIXTIETHS OF SECONDS N% E 5 mfmm m OLOJ. N J U R N E O E A T NPPD A Hs%% Patented June 22, 1954 UNITED STATES RATENT OFFICEPRESSURE-ATOMIZING TYPE OIL BURNER HAVING A HIGH-FREQUENCY VIBRA-TORY-PISTON OIL-SUPPLY PUMP Application January 30, 1952, Serial No.269,077

3 Claims. 1

This invention relates to an improved oil burner having a mechanical orpressure atomizing nozzle, supplied with liquid by areciprocating-piston pump, which is controlled by an electro-magnet,supplied with alternating current through a half-wave rectifier, so thatthe pump piston is reciprocated at the frequency of the alternatingcurrent, say for example, 3600 cycles per minute.

This application is a continuation in part of our application, SerialNo. 189,741, filed October 12, 1950.

The use of a pump of the type described as an oil supply means for amechanical or high-oil pressure atomizing nozzle has many importantadvantages over the conventional rotary pump, heretofore used for thepurpose in connection with oil burners adapted for house-heatingservice. Oil is pumped only at the rate that it is consumed; the pump isself priming; no cut-off or by-pass valves are required to respectivelylimit the minimum and maximum pressures at which oil is supplied to thenozzle; the pump stops instantly, when the power is cut off, therebyaffording a quick cut-off of oil from the nozzle; a large saving inpower is effected; the pressure of the oil supplied to the nozzle andthe energy imparted to such oil is easily and conveniently varied byvarying the voltage applied to the electro-magnet which actuates thepump.

The invention has for an object the provision of improved means formounting a high-frequency vibratory-piston oil-supply pump on an oilburner of the pressure-atomizing type.

This and other objects will best be understood from the detaileddescription of one illustrative example of the invention in theaccompanying drawings, in which:

Fig. 1 is a side elevational view of an oil burner embodying theinvention;

Fig. 2 is a sectional elevational View taken on the line 2-2 of Fig. 3and drawn to a larger scale;

Fig. 3 is a rear elevational view of the burner;

Fig. 4 is a fragmentary cross sectional view taken on the line 4-4 ofFig. 1;

Fig. 5 is a sectional plan view taken on the line 5-5 of Fig. 1;

Fig. 6 is a sectional elevational view taken on the line 66 of Fig. 3;

Fig. 7 is a cross sectional view taken on the line 1-1 Of Fig. 6;

Fig. 8 is a diagram of the electrical connections of the burner;

Fig. 9 is a side elevational view of the burner, showinga modificationin the fuel feeding means Fig. 10 is an enlarged fragmentary sectionalelevational view of the pump, showing a dia phragm and chamber thereforconnected with the outlet of the pump;

Fig. 11 is a full-size tracing taken from the screen of an oscilloscopeand showing the form of the oil pressure wave developed by the pump,when operating alone, without any pulseabsorbing means or flexibletubing between the pump and nozzle;

Fig. 12 is a similarly-made tracing showing the efiect on the oilpressure wave, when a certain length of copper tubing is introducedbetween the outlet of the pump and the nozzle; and

Fig. 13 is a similarly-made tracing showing the oil pressure wave whenthe diaphragm of Fig. 10 and the copper tubing shown in Fig. 9 are usedbetween the outlet of the pump and the nozzle.

Referring to these drawings, the invention will be disclosed withreference to its use in an oil burner structure. For other uses, wherecombustion of the sprayed liquid does not occur and it is merely desiredto spray the liquid, the airsupply and ignition provisions, hereinafterdisclosed, may be omitted.

In these drawings, a gun-type oil burner has been disclosed which, ingeneral, is of well known form, although it embodies occasionalimprovements in the burner structure and, of course, the novel fuelsupply and atomizing means of this invention.

Referring first to Fig. 6 thereof, the burner includes an air-supply fanI, mounted in a casing 2, which is suitably supported as by a floorplate 3 and an adjustable post 4. Casing 2 (see Fig. 4) has openings 5and 5' in opposite end walls 6 and 6', respectively, and a peripheraloutlet 1 (Fig. 6) leading into an air chamber 1, which overlies the fanand to which one end of a tube 8 is connected. This tube conducts allthe air for combustion and has its other end open and adapted todischarge into a furnace. Near the discharge end of tube 8 is ahigh-oil-pressure iatomizing nozzle 9 of the usual well konwn form forproducing a spray, when supplied with oil or other liquid under apressure greater than a predetermined minimum value. On the outer end ofthe tube 8 is an air director Ill for turning the air stream into thespray of atomized oil emitted from the nozzle. In the tube is aturbulator for whirling the air prior to its mixing with the oil spray,such turbulator comprising a series of spiral vanes H projectinginwardly from an annular ring H. The opening 5 in the fan casing (Fig.4) receives a frusto-conical air director E2, the flanged outer end ofwhich is clamped to end wall 6 by a ring l3, secured by screws 14 tosuch wall. The opening l2 within the air director 12 forms the main airinlet for the fan. The other opening is covered by a plate 55, which issecured to end wall 6' by screws l6 and which has a plurality ofopenings I! therethrough. The fan I has its hub fixed, as indicated, tothe shaft iii of an electric motor [9. The latter is fixed to thedescribed plate [5 by screws 26, which pass through the plate and threadinto lugs 2| on the inner end wall 22 of the motor. Between these lugsand the end wall are passages 23, leading to the openings I1 and thus tothe interior of the fan casing. Thus, air is drawn in by the fan i,partly through the main inlet I2 and partly through the auxiliary inlet,comprising the passages 23 and holes I], and forced out through outlet 1(Fig. 6) into chamber 1' and from the latter through tube 8, the airbeing whirled by the turbulator vanes H and just before it is directedby cone It into the spray of atomized oil emitted from the nozzle 9.

The particular motor shown is a very small one, say for example, a onethirty-fifth horse power, split-phase, 115 volt, 60 cycle,alternating-current motor. It customarily has ventilation openings inboth end walls and a ventilating fan (not shown) fixed to its shaftinside the casing. Motors of this type tend to run rather hot and it isdesirable to space the inner end wall 22 from the plate 45, to which itis fastened and provide for a flow of cooling air along this inner endwall. Such air, warmed by the heat exchange with the motor, is drawn inby the fan, as above described, and utilized for combustion.

The rate, at which air is supplied to tube 8,

is variable by adjustment of a damper 24 (Fig. 6), mounted on a pivotrod 25, fixed at its ends (Fig. 4) in the walls 6 and 6' and movable byturning a screw 25 (Fig. 6). The latter passes through casing 2 and isthreaded in a nut 21, w

swivelled in the damper. The head of the screw is held against the outerface of casing 2 by a spring 23, mounted on the screw and acting betweenthe inner face of the casing and a collar 29, fixed on the screw.

The oil is supplied to nozzle 9 by an electromagnetically operatedreciprocating piston pump which is mounted on one side wall of thecasings 2, as shown in Figs. 1, 3 and 5. This pump and theelectromagnet, which actuates it, are mounted in a casing, comprising amain section or body 3! and a cover 32. The lower end of the body andthe upper end of the cover are respectively providedwith shoulders 33and 34 and hubs 35 and 36, projecting in opposite directions one fromeach of the shoulders. A grommet 37, of rubber-like material,encompasses each hub and abuts the adjacent shoulder. Each grommet (Fig.5) has a circumferential groove in its outer periphery to receive a partof a supporting arm 38 and a U-shaped clamp 39, which is fixed at itsends to the arm by bolts 49. Both arms 38 (Fig. 3) project outwardly atright angles from a common support 4|, which is fixed to casing 2 byscrews 42.

Referring next to Fig.2, the body 3! of the pump and its cover 32 aremade of suitable magnetic material, and as shown of cast iron. The

upper portion of body 3| has a large cylindrical recess in which ismounted the annular coil 43 of the electromagnet. Body 3| has a holecoaxial with the magnet coil recess and extending from the latterthrough the body to the bottom thereof and fixed, as by a drive fit, inthis opening is a rod 44, which is also of suitable magnetic materialand in which is formed the cylinder 45 of the pump. Rod 44 has anintegral upward extension 45 projecting through the central opening incoil 43 and forming the core of the electromagnet. Slidable in cylinder44' is a piston 46, which extends upwardly through core 4%: and hasfixed to its upper end at a location above the upper end of the core, anarmature 41. The latter preferably has a frusto-conical lower end tocooperate with a complementary-shaped recess in the upper end of thecore 45. The frusto-ccnical face of armature 41 preferably has a seriesof brass inserts 4'? which project outwardly from its face a smallamount, preventing contact between the two cooperating magnetic facesand sticking of such faces, one to the other, by residual magnetism. Thecover 32 has a central opening 48 therein, which slidably receives thearmature, and in this opening are a series of angularly-spacedlongitudinally-extending grooves 49 to allow liquid to pass thearmature. A spring 50, which is located in opening 43, acts betweensuitable seats, one on the end wall of the opening and one-on the top ofthe armature and encircling rod 45, and tends to move the armaturedownwardly. A similar spring 5|, mounted at its ends in suitable seatsin recesses in the bottom or" the armature and the upper end of core 45,tends to move the armature upwardly. The armature is balanced betweenthese two springs, which have the same dimensions and are under the sameinitial stress. The armature is shown in its rest position midway of itsstroke. The mass of the armature 41 and rod 46 and the characteristicsof the springs 50 and 5! are so selected as to have a natural period ofvibration substantially equal to the frequency of thealternating-current supply to which the coil 43 is adapted to beconnected. As shown diagrammatically in Fig. 8, the coil 43 is adaptedto be connected to a volt, 60 cycle, alternating current source througha suitable half-wave rectifier 52, which may, for example, be a seleniumcell rectifier. Thus, when the control switches, indicated in thediagram and later to be described, are closed, the coil 43 will beenergized intermittently in pulses at the rate of 3600 per minute. Whencoil 43 is energized,

the armature 41 (Fig, 2) will be drawn down wardly toward the core 45 toactuate piston 45 on its pressure stroke, the magnetic circuit extendingthrough core 45, acrossv an axial air gap to armature 43, through thelatter and across a small radial air gap to cover 32, outwardly throughthe cover in radiating paths to the annular shell which surrounds coil43, downwardly through this shell and thence inwardly in radiating pathsto the lower end of core 45. When coil 43 is deenergized in the intervalbetween two successive energizing electric pulses, the armature 41 willmove away from core 4-5 to and above the rest position illustrated. Thestroke of the pump is variable, depending on the power applied to thecoil and the resistance en-' countered by the piston. The resonantsprings 50 and 5! serve to keep the armature 41 and piston 46 invibration with only a small amount of assistance from coil 43, leavingthe major part of the energy developed by the coil for the performanceofuseful work.

5. The pump cylinder 44 has an inlet port 53, communicating with apassage 54, which is formed in body 3| and extends horizontally outwardand thence vertically upward to a cylindrical space 55, formed. in cover32 and located above coil 43. This space is connected by the describedpassages 49 and hole 48 to the oil inlet 55, which connects with thehole 48 by means of the central opening through the upper seat of spring56. This inlet is connected by a suitable conduit, such as copper tubing51', to a suitable oil supply tank (not shown), the tubing preferablyhaving a coil 51' therein (Figs. 1 and 3). The coil 43 (Fig. 2) issuitably sealed off from the oil-containing chamber 55, as by a circularmember 58, which closely fits around core 45 and the peripheral wall ofthe coil-containing recess and has inner and outer seal rings 59 toengage such core and wall. The pump cylinder is provided with a checkvalve in its outlet, such as the ball valve 60, which is held closed bya spring Bl, acting against a seat on the upper end of a screw 62. Thelatter is threaded into the lower end of member 44 and closes the lowerend of the opening therein. The outlet valve 60 opens into an outletchamber 63, formed in member Ml, and this chamber connects with anoutlet passage 64 formed in the body 3|.

The outlet passage 64 delivers the pumped oil into a cylindrical chamber65, formed in the lower part of body iii. A cover 66, secured to thebody by screws H, provides access to the chamber and has a centraltapped opening therein which receives an outlet pipe 58. Within thechamber 65, is a block 69 of suitable resilient material, which in thiscase, .is composed of particles of ground cork held together by arubber-like binder. The block is square in cross section and its fourlongitudinal corner edges engage the cylindrical wall of chamber 65,leaving four longitudinal passages for the oil. Protuberances H3 on theend walls of this chamber engage the ends of the block and hold themspaced from the end walls to enable oil from passage 64 to flowoutwardly to said longitudinal passages and thence inwardly from thelatter to the outlet pipe 68. One purpose of this arrangement is tosmooth out the pulsations in the stream of pumped oil. The pressure ofthe pumped oil will vary in a wave which rises from a minimum to amaximum and above the lower pressure limit of the atomizing nozzle 9. Asis well known, if the pressure of the oil fed to a pressure ormechanical atomizing nozzle falls below a certain critical value, thenozzle will not produce a spray. Hence, it is essential to provide alimitin means which will maintain minimum pressures above this criticalvalue and high enough to insure that the nozzle will be operative toproduce a safe and stable spray under all conditions usually encounteredin practice.

The pipe 68 delivers the oil stream into a pressure-regulating device,which is contained in a casing H, having a cover 12, held in place byscrews 13. The pipe 68 is connected to the end of casing 1|, oppositefrom the cover, and opens into a passage 14, having a counterbored part,in which is located a ball '55. This ball is not a valve in the usualsense becauseit never closes in normal operation. Rather it is anobstruction, which may be variably positioned to variably restrict theeffective area of the passage 14, accordingly as variations in pressureof the pumped oil occur. Voltage variations in the alternatingcurrentsupply will cause variations in pressure of the pumped oil. The pressurevaries directly with the voltage and, in the present example would varyabout four pounds per square inch for each change of one volt in thevoltage of the alternating current supply. It is necessary, therefore,to compensate for fluctuations in line voltage, which might under somecircumstances render the nozzle inoperative and in others would causetoo wide variations in the firing rate for satisfactory operation. Theobstruction i5 is one way of compensating for such voltage variationsand thereby maintaining the oil pressure at the nozzle within acceptablelimits. By oil pressure, is meant the pressure, which shows on a gauge,that is average pressure. The obstruction ball 15 is moved by a plunger'56, fixed to one end of a rectangular frame T5. The other end of thisframe has fixed thereto one end of a closed bellows 13, containing aspring i9, tending to separate the ends of the bellows. The other end ofbellows i8 is fixed to one end of a second rectangular frame til, theother end of which is fixed to the cover l2, and, as shown, by means ofa screw 6%, threaded into an opening in cover 12. The frame at hasopenings 36' to slidably receive one end of frame i? and limit itsmovement toward ball 75. The outer end of such opening is closed by ascrew 82. By removing screw $2, screw 8| may be turned to vary theposition of frame and thus the force exerted by spring "59 tending toexpand the bellows and draw plunger "iii to the left to decrease therestriction in passage M. In the example herein shown, the bellows willnot be contracted until the oil pressure reaches pounds per square inchand ball 75 presents the least restriction. This is the position of theball for the low limit of voltage regulation, say for example 100 volts.Increase in the line voltage causes the pump to develop more pressurewhich tends to contract the bellows and move the frame ll and plunger'56 to the right to increase the restriction of passage Hi and cause agreater pressure drop in the oil. On a decrease in the voltage suppliedto coil 43, the pump will develop less pressure and the variableobstruction 75 will be moved to the left to decrease the restriction inpassage 14, decreasing the pressure drop and thereby increasthe pressureof the oil supplied to the nozzlev The obstruction would be in its midposition a, normal voltage, say for example, volts. and would move tothe right or left to increase or decrease the restriction as the voltagerises or illlS respectively. With this arrangement, the pressure of thepumped oil may be maintained substantially constant over a range ofvoltage variations from 100 to 130.

As shown, a light spring 83, acts between the ball 75 and a shoulder onplunger 15, but this spring is not strong enough to move the ballagainst the seat in the counterbore of passage 14 during normaloperation. It merely prevents the ball from rattling.

The outlet of the pressure-regulating device is connected by a suitableconduit to the atomizing .nozzle 9. As shown, this conduit includes acopper tube 84 (Fig. l) which extends upwardly from the outlet of theregulator, has a coil 84' formed therein and then enters through a notchin the side wall of easing 2 into the rear end of the chamber 1', whereit extends forwardly,

as shown in Fig. 5, and is connected by a union '81, which are mountedin insulators 88 and have their rear ends connected by wires 89 with thehigh tension terminals Gil (Fig. 6) of an ignition transformer, mountedin a case 9|, fixed on top of casing 2.

The nozzle 9, turbulator l l--l l, and electrodes 81 may be supported inany suitable way in tube 8, desirably in the manner indicated in Fig. 5,to permit convenient withdrawal of these parts in assembled relationfrom the tube 8 and the aligned chamber '1', after the closure plate 92for the rear end of chamber '5' and its retaining screws 93 have beenremoved. To this end, a pair of rods 94 are fixed at one end to the ringH of the turbulator, one at each of two diametrically opposite pointsthereon, and these rods extend rearwardly in spaced, parallel throughtube 8 and through chamber 1, termihating in outwardly-bent parts 95,the outer ends of which are received one in each of two notches formedone in each of two opposite side walls of the casing 2. Theplate 92retains these ends 95 in their notches. Fixed at its ends to rods 94 andspanning the space between them, is a support 9G having a central hub,in which the nozzle-supporting tube 36 is fixed, and two upper hubs inwhich the insulators 8B are fixed. The support as also has a centraldepending hub, to which an air-distributing bafiie 91 is fixed. It willbe clear that when plate 92 is removed, the ends 95 of rods 94 arereleased. The high tension wires 89 will then be disconnected fromterminals to and the oil pipe 8d will be disconnected by removing union85 or 35', after which the nozzle 9, its support til, the electrodes 8?with their insulators 23 and the turbulator i may be withdrawn forinspection, cleaning or repair.

The invention includes a control switch 98 for the coil 43 or" theelectromagnet. As shown in Fig. '8, this coil, the switch es, thehalf-wave rectifier 52, and a variable resistor 919 are included inseries in a circuit lllil which is shunted across the wires it! and H32that supply the fan motor I9 and the primary lbs of the ignitiontransformer, the secondary Hi l of which is connected by the describedwires 89 to the ignition electrodes ill. Any suitable control may beprovided to start and stop the motor i9 and ignition transformer andsuch a control has been indicated, simply and schematically, by athermostat switch lt5, which usually is responsive to temperature in thespace to be heated and con nects wire ill! to a wire it'd, when there isa demand for heat. The wires 1?. and W6 are adapted for connection to asuitable source of electricity, say for example a 115 volt, 6O cycle,alternating-current source. The electromagnet 43 is adapted to beenergized only after the air supply has been well started by the motor.Thererelation 7 means of the variable resistor so.

fore, the closingof switch 88 is delayed, as by 8 quency of thealternating current. Theresistor' I0! is shunted across the rectifier toallow a small amount of current to flow to coil 53 in the intervalsbetween the aforesaid pulses for the purpose of demagnetizing the coreto avoid possible sticking of the armature thereto.

The switch 93 is shown in Figs. 1 and 4 as a micro-switch, mounted on anangle-iron shelf Hi8 fixed to the end wall of a cylindrical case I89,having its other end closed by a disk cover lit, secured by screws illto the case. This case His is supported by four angularly-spaccd armsill from the described ring l3, leaving openings H3 through which airmay enter to the main'inlet opening E2 of the fan. The switch 98 has anactuating plunger 93 and suitable spring means (not shown), tending tomove the plunger to the left, as viewed in Fig. l, into closed position.The switch plunger 88 is actuated by a plunger 1 M, which is slidablymounted in a hub on the end wall of case $89. This plunger lid is shownheld in its right hand and switchopening position by the flanged andclosed outer end of a tube H5, which is slidably mounted on a rod llil,having a flanged end, as indicated to the drive shaft iii of motor it. Aspring HT encompasses rod lie and acts between the flange on the rod andthe adjacent end of tube H5 to force the latter to the right and pressthe plunger lit and the plunger 98 of switch 98 to open the switch. Theflanges of rod H6 and tube H5 are interconnected by flexible metal bandsHS, each having fixed to it at a point betion and continuing until itdisengages from the plunger 5 M. A small spring iii] takes up the lostmotion and holds plunger l id in contact with plunger 93 and out ofcontact with the outer end of the rotating tube i It. Spring 213 is notstrong enough to move the switch plunger 38 against its internalactuating spring (not shown).

In operation, the rate of flow of oil from the V nozzle 9 is controlledby varying the power applied. to coil 33, which ma be done in anysuitable way. As an illustrative example, the variable resistor es isshown for the purpose. With a selected size of atomizing nozzle, therewill be a certain amount of load imposed on the pump and the powerapplied to the magnet is adjusted to that load. Preferably, the magnetis designed to operate the piston at slightly less than full stroke forthe largest size nozzle to be used. Lesser rates of flow can then besecured by in- 'cluding more resistance in the circuit, as by Slightlyless than full stroke operation is desirable to avoid noise inoperation. It should be noted that the nozzle selected does not have tobe operated at the rate which is specified for it to be operated. Theone size nozzle can be operated at different rates by varying thepressure of the oil supplied to the nozzle, such pressures beingvariable, as

for example from a minimum of 35 p. s. i. to a maximum of 200 .p. s. i.by varying the voltage applied to the magnet of the pump. Havingselected the nozzle and secured the desired rate of oil flow, the'rateof airflow is adjusted by means of screw 28. This adjustment may be madefor a high percentage of 002 because the oil flow is delayed until goodair flow is produced.

in order to avoid smoky operation during the starting and stoppingintervals of each run of the burner.

In normal operation, on a demand for heat from the burner, switch Icloses and starts the motor it, which drives fan i causing the latter toproduce a flow of air through tube ii and past the turbulator vanes ll.As soon as the fan nears full speed, the centrifugal switch 98 closes toconnect coil 43 to its alternatingcurrent supply, and the fuel pump isset in action. The ignition transformer may be energized with the motor19, as shown, or it may be delayed until coil 43 is energized. With thepump in operation, oil is fed to nozzle 9 and emitted in a finelyatomized conical spray. The air mixes with this spray and the mixture isignited by sparks produced between the electrodes 81.

As differentiated from the common means of supplying oil to a mechanicalatomizing nozzle, the stroke of the fuel pump is variable according tothe load and according to the power applied. All of the oil pumped goesto and through the nozzle. Oil is supplied only at the rate it isconsumed. None of the oil is by-passed, as is the case with the usualrotary pump driven at constant speed by an electric motor. There thepump is designed to pump oil at a far greater rate than it is used andall excess oil is bypassed. The rotary pump may by-pass as much as 17gallons per hour all of which has to be raised to the high pressure sayfor example 100 p. s. i. There, a cut-ofi valve prevents flow of oil tothe nozzle until a predetermined minimum oil pressure has beenestablished and a relief valve opens a by-pass as soon as apredetermined maximum oil pressure has been established. There, widefluctuations in line voltage would slow the motor, fan and pump but notso much as to lower the oil pressure below the critical lower limit atwhich the nozzle is inoperative to produce a spray.

With a pump of the character described, as the line voltage falls, thepressure of the pumped oil falls with it in direct proportion and may goall the way to zero or until the pump outlet valve closes and thisoutlet valve is provided merely as a check valve and not to establish alower limit of oil pressure. Actually, in the present pump, operatedwith the described current and supplying a pressure atomizing nozzlerated at one gallon per hour (when operated at a pressure of 100 poundsper square inch, and without the voltage-pressure control hereindisclosed), the oil pressure varied 4 pounds per square inch for eachone volt change in voltage. The Underwriters require safe operation of aburner at from 85% to 115% of normal voltage or from 93 to 127 volts,assuming normal voltage to be 115. A variation of 29 volts would mean avariation of 115 pounds in oil pressure which of course is altogethertoo great to be tolerated. The firing rate would vary widely and alsothe pressure might very well drop so low that the nozzle would cease toproduce a good spray. Hence, the regulator disclosed is essential in asystem of this kind. It is not a pressureregulator of the ordinary type,in which a valve opens at a predetermined pressure and by-passes excessoil to keep the stream pumped to the nozzle at a constant pressure. Sucha valve would be useless here because the instant it opens, the pump isunloaded and goes to full stroke operation, becoming very noisy. Whatthe present regulator does is to compensate for variations in linevoltage. As long as this voltage is normal, the regulator does notfunction. It comes into play only when the line voltage increases ordecreases from normal and. then it prevents the Wide variations in oilpressure that would otherwise occur.

The burner shown in Fig. 9 is the same as that shown in Figs. 1 to '7inclusive except that the regulator that compensates for variations inline voltage is omitted and the outlet of the pump is connected by alength of copper tubing IN to one end of the tube 86 which carries onits other end the atomizing nozzle 9. Also, the pump, at its outlet end,is somewhat differently constructed, as will be explained. Variations inline voltage may be prevented from causing substantial variations in oilpressure by any suitable electrical regulator which will function tordnaintain constant current in the circuit of coil The electromagneticpump is essentially the same as before but the chamber 65 and resilientmember 69 have been replaced by a diaphragm I22 and a chamber I23,formed in the pump body I24 above the diaphragm and in communicationwith the outlet of the pump. As shown the marginal portion of thisdiaphragm is rigidly held by clamping it between a cap I25 and the body,the cap being suitably secured to the body as indicated. The upper faceof the cap has a shallow conical recess I25 therein located immediatelybelow the diaphragm. The cap is formed for mounting in the lowerresilient grome met 37 in the same way that the lower portion of thepump body 3! of Fig. 2 was formed. The lower end of the member 44 stopsshort of cham-, ber I23 and the plug l2'i, that is threaded into thelower end of member M to provide a seat for the spring 6! of the checkvalve til of the pump, has a passage [28 therethrough to connect thepump outlet to the chamber H23. The pump outlet passage 64 connectsdirectly with the copper tube I21. Qtherwise the pump is constructed andoperates as heretofore described.

As one suitable example, the diaphragm I22, herein shown, is made ofbrass, has a thickness of .009" and the circular area that is exposed tooil pressure is 1 4" in diameter. The lower chamber I26 has the samediameter and its maximum depth is .027. The outlet of the pump isconnected to the rigid nozzle supporting tube 86 by g" copper tubingwhich has a length of 22 The operation of the electromagnetic pump, whenits outlet is connected directly to the inlet of an atomizing nozzle ofthe mechanical or high-oil-pressure atomizing type, without anysubstantial length of intervening conduit and Without thepulsation-modifying means of this invention is illustrated in Fig. 11.The graph there shown is a tracing from the screen of an oscilloscope,arranged to show the oil pressure at the inlet of the atomizing nozzle.The nozzle used was one rated for 1 gallon per hour at pounds per squareinch. As will be seen, the pressure rises sharply on the pressurestroke, as indicated by the part I35! of the graph, from a minimum of58.8 p. s. i. to a maximum of 141.2 p. s. i. and then decreases on thesuction stroke of the pump, as indicated by the part It! of the graph,to the aforesaid minimum. The very steep rise in pressure results in asevere impact, which tends to cause vibration in parts attached to thepump. A very wide variation in oil prespurpose.

11 sure is produced, in this case plus or minus 41.2 from the averagepressure of 100 p. s. i. indicated by the line I32 of the graph, or atotal variation of 82.4 p. s. i. In particular, the minimuminstantaneous pressure values are too low for producing What may becalled a safe stable spray from a nozzle of the type described, whereatomization is affected by the action of centrifugal force on therelease of a very rapidly whirling oil stream. Merely-to connect amechanical atomizing nozzle directly to the outlet of the pump will notproduce results, which are satisfactory for commercial use.

It is necessary, as a practical matter, to provide in an oil burnerbetween the outlet of the pump and the atomizing nozzle a conduit ofsubstantial length, and, usually, tubing which is somewhat flexible isused for the purpose because it readily be bent to the form required.Usually, copper tubing is used for the The use of such tubing has anadverse effect on the operation of the pump and nozzle. Harmonics areproduced in the pressure wave. Increases in length of the tubing causeresonance at decreasing orders of frequency. The spread between maximumand minimum instantaneous pressures increases with increases in lengthof the tubing. Fundamental resonance occurs with a tubing length ofabout feet and the pressure variations then are substantially plus orminus 100%. Fig. 12 shows what occurs with the use of a inch length offa" copper tubing. The

graph 133 shows a transition between the fourth and third harmonics withthe wide spread in pressure variations of plus or minus 55.3%. Thedotted line ltd is the estimated 60 cycie fundamental wave.

In Fig. 13, is shown the pressure wave as pro-- duced by the pump ofFig. 10, as above defined, and a 22 length of f g inch copper tubingbetween the pump outlet and the nozzle, which is rated at 1 gallon perhour at a pressure of 100 pounds per square inch. The diaphragm i522,having the dimensions above set forth, modifies a pressure wave verysimilar to that shown in Fig. 12 so that the pressure variations aresubstantially reduced to plus or minus 15.5% and in particular theminimum pressures are maintained well above the critical pressure atwhich a safe stable spray would be formed, as for er:- am'ple 65 to '70pounds per square inch. The pressure wave !35 has three harmonics buttheir amplitude has been very greatly reduced. The dotted line E38represents the estimated 6-0 cycle fundamental wave.

The diagrams of Figs. 11' and 12 illustrate operations of theelectromagnetically-operated pump that are unsatisfactory for thepurpose or" producing a satisfactory spray from a nozzle of themechanical or pressure-atomizing type. Fig. 13 clearly shoWS how thediaphragm 22 renders the operation of a high-frequencyreciprocating-piston pump of the class described suitable for use as anoil supply means for a mechanical atomizing nozzle. The member 69 andchamber 65 will function in a similar way. The output of the pumpnormally is in the form of a saw-toothed pressure wave such as shown inFig. 11 having amplitude which is excessive for the purpose and, inparticular, minimum pressure values below those at which a safe andstable spray can be produced. The condition is made worse as shown inFig. 12 by the use of the conduit that is necessary to connect the pumpand nozzle. The difiiculty is thought to be due in duit, presentingconsiderable volume between the pump andnozzlaand in part to theelasticity of the conduit itself. Elasticity at the outlet of the pumpabsorbs some of the vibrations from the severe impacts of the pressurestrokes of the pumps and limits the adverse effects that would otherwiseoccur in the conduit intervening between the pump and nozzle. Controlledelasticity at the outlet of the pump is preferred. Elasticity, which isdistributed along the conduit or at the nozzle is not as good because ittends to prevent the sharp cut-oil? that is desired, when the power tothe pump is cut-off, in order to prevent afters'quirt at the nozzle. Thediaphragm I22 has been shown to provide the amount of elasticity locatedat the right place to smooth out the pressure wave of the pump andmaintain the instantaneous minimum pressure values well above thecritical pressure at which a safe and stable spray can be produced bythe nozzle.

The invention thus enables a high-frequency reciprocating-piston pump tobe used as a means of supplying liquid to a mechanical atomizing nozzleand very important advantages to be se cured without the accompanyingdisadvantages; and even dangers, that otherwise might follow from lowinstantaneous pressure values and the resulting failure of the nozzle toproduce an effective spray.

What is claimed is:

1. In an oil burner, an air-supply fan, a casing for the fan havinginlet and outlet openings, a tube connected at one end to the outletopening and conducting the air for combustion, av motor for driving thefan, a pressure-atomizing nozzle in said tube near the other endthereof, a re ciprocating-piston oil-supply pump, a conduit connectingthe pump to said nozzle, an alternating-current electromagnet connectedto reciprocate said piston at the frequency of the alternating current,said pump having two spaced parallel shoulders and cylindrical hubsextending in coaxial relation in opposite directions from saidshoulders, grommets of rubber-like material one encompassing each huband abutting the adjacent shoulder, and a support on said casing havingspaced parallel outwardly-projecting arms supporting said grommets onein each.

2. In an oil burner, an air-supply fan, a casing for. the fan havinginlet and outlet openings, a tube connected at one end to the outletopening and conducting the air for combustion, a motor for driving thefan, a pressure-atomizing nozzle in said tube near the other endthereof; an oil supply pump comprising a body having a cylinder with aninlet and an outlet, a piston reciprocable in said cylinder, a valve forclosing the outlet, and a spring tending to hold the valve closed, aconduit connecting the outlet or the pump to said nozzle, analternating-current electromagnet connected to reciprocate said pistonat the frequency of the alternating current, said pump having two spacedparallel shoulders and cylindrical hubs coaxial with said cylinder andextending in opposite directions from said shoulders, two grommets ofrubber-like material one encompassing each hub and abutting the adjacentshoulder, and' a support on said casing having spaced parallel.outwardly-projecting arms supporting said grommets one in each.

3. In an oil burner, an air-supply fan, a casing for the fan havinginlet and outlet openings, a tube connected at one end to the outletopening and conducting the air for combustion, a motor part to thecompressibility of the liquid in a con for driving the fan, apressure-atomizing nozzle in said tube near the other end thereof, areciprocating-piston oil-supply pump; a conduit connecting the pump tosaid nozzle, an alternatingcurrent electromagnet connected toreciprocate said piston at the frequency of the alternating current,said pump having two spaced parallel shoulders and cylindrical hubsextending in coaxial relation and in opposite directions from saidshoulders, grommets of rubber-like material one encompassing each huband abutting the adjacent shoulder, each grommet having in its peripherya circumferential groove, and a support on said casing having spacedparallel outwardly projecting arms each having a semi-circular edgeengaged in one part of said groove, a member hinged at one end to theouter end of each arm and having a semi-circular part engaged in anotherpart of said groove, and a fastener for holding the other end of eachsaid member to its arm.

References Cited in the file of this: patent UNITED STATES PATENTSNumber Name Date Waters Apr. 13, 1886 Serve Nov. 23, 1897 Meyers Feb. 5,1924 Persons Dec. 29, 1931 Pirsch Jan. 10, 1933 Clarkson Aug. 22, 1933Rodler Apr. 20, 1937 Holthouse June 16, 1942 Bremser Sept. 4, 1945Holthouse Aug. 27, 1946 Pinkerton et a1. Oct. 28, 1947 Dickey et al June7, 1949 Rosenthal Sept. 13, 1949 Simmons Jan. 17, 1950

